The correct maths in c# for random point from a given pos

Unity Engine
1

Hi all,

Sounds simple enough…and it seemed to in Javascript :wink:
Now I have gotten my feet wet in unity I am migrating the tutorials + my own stuff over to c#.

My question is, given a specific point (0,0,0) I needed to get to a random position and angle away from this point. For simplicity lets say it can be any distance and any angle.

This is straight forward trigonometry, but I need to use Quaternions, and my Quaternion skills are still junior although I have read a number of tutorials.

if (Input.GetButtonDown("Fire1")  target)
	    {
			// initially for the first tests, lets just set up the camera to change
			// when the player hits the space bar
			Random.seed = (int)System.DateTime.Now.Ticks;
		
			// get some random values for teh camera distance and angle
			int camDist = Random.Range(20,60);
			int camAngle = Random.Range(45,135);
			
			// point on a cricle : (x,y) = (x+d(cos*angle),y+d(sin*angle))  
			x = camDist*Mathf.Cos(camAngle);
			y = camDist*Mathf.Sin(camAngle);
	
			// update distances
			currentDistance = camDist;
			camDistance = currentDistance;
			y = ClampAngle(y, yMinLimit, yMaxLimit);
	 		       
	 		// Qaternion.Euler : Returns a rotation that rotates x degrees around the x axis. y degrees around the y axis. z degrees around the z axis. 
	        Quaternion rotation = Quaternion.Euler(y, x, 0);
	        Vector3 targetPos = target.position + targetOffset;
	        //Quaternion direction = rotation * -Vector3.forward;
			// must create a quaternion that accepts a rotation quaternion and vector 3 as arguements
			
			Quaternion direction = Quaternion.AngleAxis(rotation, Vector3.forward);
			
	        Vector3 targetDistance = AdjustLineOfSight(targetPos, direction);
			currentDistance = Mathf.SmoothDamp(currentDistance, targetDistance, distanceVelocity, closerSnapLag * .3);
	        
	        transform.rotation = rotation;
	        transform.position = targetPos + direction * currentDistance;
	    }

if you see the line "//Quaternion direction = rotation * -Vector3.forward; " - this was what I was doing in javascript, but unity has issues converting this calculation to a quaternion. I tried angle axis - but this requires a float as an argument, not an already created Quaternion.

I have done some looking into this to try and find the correct code but I guess just need a kick in the right spot. Some help would greatly appreciated.

Thanks.

2

This should have given you the same message in js as well.

<Quaternion> * <Vector3> = <Vector3>

the resulting vector, is the original vector rotated by the quaternion.
I don’t quite follow what you are trying to achieve, but perhaps you can just change this line:

Quaternion direction = rotation * -Vector3.forward;

to

Vector3 direction = rotation * -Vector3.forward;

my guess is that in javascript you just had:

var direction = rotation * -Vector3.forward;

i.e. direction was a Vector3…